Observations on the axial filament complex of the human spermatozoon

Abstract

The two central fibers of the axoneme of the human sperm tail are interconnected by regularly spaced ribs, which are perpendicular to the longitudinal axis of the fibers. The central sheath is composed of two threads spirally arranged around the central fibers and with points of contact with these fibers at the levels of the interconnecting ribs. Regularly spaced spokes project from the spiral threads toward the alpha fibers, arranged so that alpha fibers in one half of the axoneme, divided by the plane of the central fibers, receive spokes from one spiral thread, whereas the other spiral thread provides the other half of the axoneme with spokes. Some suggestions are made on the functional implications of this axial spiral complex in relation to flagellar motility.